Method and system for determining bilirubin concentration

Abstract

A system and method embodying the invention can be used to detect a characteristic or condition of a patient. A method embodying the invention may include the steps of illuminating a portion of a skin of the patient with light, detecting a frequency spectrum of light scattered from the skin, determining, from first and second portions of the spectrum, a first parameter indicative of a blood content of the skin and a second parameter indicative of a melanin content of the skin, determining, from a third portion of the spectrum, a third parameter indicative of an uncorrected bilirubin concentration, and calculating a corrected bilirubin concentration based on the first, second and third parameters.

Description

RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 09 / 589,403, filed Jun. 8, 2000 now abandoned, which is a continuation-in-part of U.S. patent application Ser. No. 09 / 286,649, filed on Apr. 6, 1999 now U.S. Pat. No. 6,192,734, which is in turn a continuation of U.S. patent application Ser. No. 09 / 054,490, filed on Apr. 3, 1998 now U.S. Pat. No. 5,924,981, which is in turn a continuation-in-part of U.S. patent application Ser. No. 08 / 904,766, filed on Aug. 1, 1997 now U.S. Pat. No. 6,045,502, which is in turn a continuation-in-part of U.S. patent application Ser. No. 08 / 621,182, filed Mar. 21, 1996 now abandoned, which in turn is a continuation-in-part of U.S. patent application Ser. No. 08 / 587,949, filed on Jan. 17, 1996 now U.S. Pat. No. 5,860,421. The contents of these applications are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to instruments that require cal...

AI Technical Summary

Benefits of technology

"The invention provides a simple and accurate apparatus and method for measuring a patient's bilirubin concentration using electromagnetic radiation. The instrument embodying the invention utilizes fiber optic waveguides to direct and conduct reflected or dispersed radiation back to a sensor. A calibration device, such as a gel, can be interposed between the material or tissue being measured and the instrument to improve accuracy. The instrument measures the amplitude of reflected or dispersed radiation at different wavelengths to determine the blood content of the material or tissue and the uncorrected or corrected bilirubin concentration. The method involves illuminating a portion of the skin with light, detecting the frequency spectrum of light scattered from the skin, and calculating the corrected bilirubin concentration based on the parameters indicative of blood oxygen content, melanin content, and scattering."

Problems solved by technology

Although others have proposed calibration fixtures that compensate for these variations in instrument performance, none have provided a simultaneous solution to both the calibration issue and the problems associated with the spread of infection in a medical setting.

Furthermore, calibration devices that are designed to be reused can become damaged by sunlight, temperature, humidity and other effects, which could lead to errors in calibration.

However, neither of these approaches involves an inexpensive calibration target that can be easily discarded after each use.

In addition, neither of these systems prevent a user from taking a measurement without going through a calibration step.

This approach, however, is neither simple nor inexpensive.

Again, however, this approach does not involve an inexpensive, disposable calibration device.

However, the boot is not present during the measurement and there is no provision to prevent reuse of the boot.

Newborn infants and prematurely born infants are particularly susceptible to hyperbilirubinemia.

Often this is due to the lack of functioning glucoronyl transferase enzyme in their liver, or excessive red blood cell breakdown associated with erythroblastosis fetalis.

Of course, this invasive approach requires that blood be drawn to perform the test.

Unfortunately, these devices have failed to give satisfactory correlations when used over a heterogeneous population.

Since patient populations are rarely homogeneous, transcutaneous bilirubin measuring methods have not been widely accepted clinically.

That approach, however, has not been approved for use in the United States, although it is used for screening purposes in some U.S. institutions.

In addition, that approach does not account for variations in skin color and thickness.

This approach does not have a quantitative accuracy required to have a high correlation to serum bilirubin.

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